EXAMINATION OF NORMAL AND ABNORMAL URINE. 477 



Acetone is recognized in the following manner : 500 c.c. of urine 

 are acidified with a few drops of hydrochloric acid and distilled. To 

 the distillate a few drops of iodine solution (1 iodine, 2 potassium 

 iodide, 100 water), and of potassium hydroxide are added. If acetone 

 is present a characteristic yellowish-white precipitate of iodoform is 

 formed. 



Urinary deposits (sediments). Normal urine is always clear, but 

 occasionally, and particularly in abnormal conditions, it is turbid. 



Urine may be turbid when passed, and this indicates an excess 

 of mucus, or the presence of renal epithelium, pus, blood, chyle, 

 semen, bile, or phosphate or urate of sodium in excess, etc. A 

 turbidity subsequent to the passage of the urine is generally due 

 to the precipitation of phosphates or tirates, or it may result from 

 fermentation or decomposition. Either of the substances named will 

 form a deposit on standing. 



When such a deposit is to be examined, a few ounces of the urine 

 should be set aside for several hours in a tall, narrow, cylindrical 

 glass ; when the sediment has collected at the bottom, the supernatant 

 urine may be decanted, or the sediment may be taken out by means 

 of a pipette for examination. 



Sediments are either organized or unorganized. To the first 

 belong : mucus, blood, pus, urinary casts, epithelium, spermatozoids, 

 fungi, infusoria, etc. ; to the second belong: uric acids, u rates, cal- 

 cium oxalate, phosphate, or carbonate, magnesium-ammonium phos- 

 phate, cystin, hippuric acid, etc. 



The chemical examination of any urinary sediment should always 

 be preceded by a microscopical examination, which latter is in many 

 cases the only way of determining the nature of the sediment, espe- 

 cially of the organized substances. Most of the unorganized and 

 either crystalline or amorphous sediments may be easily recognized 

 by chemical means. 



Urates of ammonium, calcium, and sodium dissolve on heating the 

 urine, and are reprecipitated on cooling. The murexid test is used 

 in addition. 



Phosphates of calcium or ammonium-magnesium dissolve in acetic 

 acid, and ammonium molybdate dissolved in nitric acid produces a 

 yellow precipitate on heating. 



Calcium oxalate is insoluble in acetic, but soluble in hydrochloric 

 acid, from which solution it is reprecipitated on neutralizing with 

 ammonia. 



